Since we don't know your reasons for no alcohol, here are my suggestions on how to do it.
Reasons for not wanting to ferment or have alcohol in your soda:
1. Religious reasons
2. Don't want the kiddies to get drunk
3. Don't want your bottles to explode
4. Don't want strong yeasty taste
5. Impatient
Solutions:
1. Force carbonate, guaranteed no alcohol from fermentation. You'll probably get some if you're using flavoring extracts, though. If you're against the alcohol in extracts, then use real fruit/roots and don't ferment. If you're okay with the amount of alcohol from flavorings, then you probably won't see much more from fermenting correctly with champagne yeast.
2. Either method is fine. Your kiddies won't get drunk, because there's no bulk fermentation step to really boost alcohol.
3. Use plastic bottles, or force carbonate.
4. Either method is fine. Use champagne yeast rather than ale yeast if you ferment because it has cleaner flavor, not because it makes no alcohol.
5. Force carbonate, it's quicker.